What Causes Car Shaking When the Air Conditioner is On?
1 Answers
Car shaking when the air conditioner is on can be attributed to the following reasons: 1. Spark plugs with carbon deposits: After prolonged use, spark plugs accumulate carbon deposits. If not cleaned in time, this reduces the engine's torque output, causing shaking when the AC is turned on. To clean, soak the spark plugs in a container with white vinegar for 2-3 hours (or 4-5 hours for severe cases), then scrub with a stiff brush to remove the carbon deposits. Rinse with gasoline, let them air dry, and they will be ready for use. 2. Intake valve carbon buildup: Older cars typically have a normal cylinder pressure of 10.5, while newer models may range above 11 or 12. Abnormal cylinder pressure can cause the car's computer to detect misfires, automatically cutting off fuel supply and leading to shaking during startup until the engine fails to start. This issue can be resolved by cleaning the intake valve carbon deposits, either by manually scrubbing after removing the intake manifold or using cleaning agents. Additionally, driving at high speeds (above 4000 RPM) can help burn off carbon deposits inside the cylinders. 3. Use of inappropriate fuel: The fuel octane rating indicates its resistance to knocking. Higher-grade fuel extends the lifespan of the catalytic converter and reduces emissions. Different engine compression ratios require different fuel grades. Using the wrong gasoline can cause severe carbon buildup, leading to shaking when the AC is on. Generally, engines with a compression ratio below 7.5 should use 90-octane fuel, those between 7.5–8.0 should use 90 or 93, those between 8.0–10.0 should use 93 or 95, and those above 10.0 should use 97-octane fuel.
